A hydraulic fracture propagation model considering anisotropy of bedding shale

ABSTRACT: The exploration and development of shale oil and gas as an essential unconventional energy has attracted much attention, and the multi-cluster volume fracturing of horizontal wells has become an essential way of its exploitation. Bedding development is a typical feature of shale, resulting in anisotropy along and vertical bedding direction, including rock mechanics anisotropy. The anisotropy of shale and the properties of the bedding interface affect the propagation path of hydraulic fractures and the complexity of the final fracture network. Therefore, it is necessary to explore the influence of the anisotropy of bedding shale on hydraulic fracture propagation. In this paper, the shale reservoir is considered a porous elastic medium, and a three-dimensional finite element fluid-structure coupling finite element model considering the interface of shale bedding is established. The model integrates the anisotropic constitutive equation and considers the fluid flow and rock mechanical anisotropy caused by bedding development. Based on the cohesion theory, the energy release rate is used as the criterion to judge the hydraulic fracture. The hydraulic fracture propagation model is established considering the hydraulic fracture's dynamic fluid and fluid loss. The results show that the propagation of hydraulic fractures in stratified shale is influenced by reservoir anisotropy.